This paper describes the speed control of a Stirling engine by means of phase-angle variation. The type of Stirling engines in our study is limited to a displacer/piston twin-cylinder engine. The control system, we designed, is characterized by the direct displacer-drive with a pulse motor which is numerically controlled by a micro processor to keep constant speed, for example.
In order to predict the characteristics of the control system and to optimize system parameters, we derived a second order differential equation linearized by approximations, and also developed the program for numerical simulations.
The control system is actually applied to the small Stirling engine made for our experiments. The engine speed was controlled without unstable speed variations. As one of the extended applications of the control system, self-starting of the engine was examined and confirmed to be possible.

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To prevent marine pollution by oil discharged from ships, the development of oil detecting devices of high performance and reliability has been internationally required. In the report, the performance of a detecting device of oil/water interface being newly developed at the Institute was investigated.
In the tank cleaning procedure carried out on tankers during the navigation, the residual oily water is gathered to a slop tank on board. In spite of the fact that it is of great importance to detect the interface between oil and water in the tank in order to prevent oil from being discharged overboard, there is the fatal defect in the existing detection techniques that the residual oil of high viscosity adheres tightly to the detector head. Accordingly, the new detecting device of high reliability, which can effectively distinguish oil layer from water even when a little bit of oil of high viscosity may adhere to it, has been developed by applying electromagnetic induction method, and the performance of the device was experimentally investigated.

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The thermo-model block diagram of induction motors for the temperature rise and time characteristics of the continuous operation are introduced. Numerical values of each constants for block diagram are calculated.
The thermo-model block diagram has two inputs and two outputs. Two inputs are copper loss and iron loss, and two outputs are temperature rise characteristics of coil and iron core. Copper loss is calculated from the equivalent circuit of induction motor and iron loss is measured. When induction motor is operated intermittently, copper loss is also changed intermittently and iron loss is changed when the applied voltage is varied.
If copper loss and iron loss depending on intermittent operation are applied to input points of the block diagram, then the temperature rise characteristics of coil for intermittent operation are derived.
The errors calculated by these method are within about 2°C for temperature rise and 2 minutes for time constant.

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Various useful data for designing of the shrink-fit shaft coupling of marine shafting have been obtained by the pulling-up and slip torque tests conducted on the coupling models.

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These days, according to the up-going price of the fuel oil, the selection of the marine engine type seems to be decided only from the view point of the economy. Resultantly the big ships, that used to adopt the steam turbine engine, have been mounting the diesel type engine.
No body doubts that the internal combustion engine like the diesel engine furtherly surpasses the external combustion engine on the rate of fuel consumption, however, the diesel engine has some undesirable features as marine engines. One of them is that it is difficult for the engine to keep the output at 85% MCR without suffering from the thermal and/or torque load to the engine when the fluid resistance of the ship submerged hull increased by the foulness due to aging progression or encountering rough sea condition. The another is that it requires us much more maintenance works than the other type of engine.
Meanwhile, the type of controllable pitch propeller is considered to save effectively those weak points on the propulsion diesel engine. In order to clarify these points, a comparison between the fixed pitch propeller installed motor ships and the controllable pitch propeller ones is tried to list up on this report, considering from an actual experience on the CPP equipped big ship for 400 days.
Also, the affection to the diesel driven propulsion which has been brought about by the aging increase of the hull submerged area fouling as well as rough sea condition, has been measured and described on the ship's diesel engine load diagram for the purpose of easy understanding. And through the actual experience, viewing from the operational stand point the advantage of the cppdiesel equipped ship on several phases is stated on this report.

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